Air chuck



Oct. 30, 1951 v. v. K. SUNDT AIR CHUCK 4 Sheets-Sheet 1 Filed April 9,1947 INVENTOR $0 van Kra gh Sundz BY g ATTORNEY Oct. 30, 1951 v. v. K.SUNDT 2,573,156

I AIR CHUCK Filed April 9, 1947 4 Sheets-Sheet 2 as I FIG. 2.

2) '///fl INVENTOR.

A Vigo uanKroghSaudi BY 36 ATTORNEY.

Oct. 30, 1951 v. V. K. SUNDT AIR CHUCK Filed April 9, 1947 4Sheets-Sheet 3 I N VEN TOR. Vz'go uanKrogh Sandi BY 5&1

ATTORNEY.

V. V. K. SUNDT AIR CHUCK Oct. 30, 1951 4. Sheets-Sheet 4 Filed April 9,1947 35 ull INVENTOR. Vig'o uonKmghSuncZt BY @MQZJM ATTURNEK PatentedOct. 30, 1951 FFlCE AIR CHUCK Vigo V. Krogh Snndt, Madison, Wis,assignor to Gisholt Machine Company, Madison, Wis., a corporation ofWisconsin Application April 9, 1947, Serial No. 740,436

4 Claims.

This invention relates to an air chuck of the collet type for high speedlathes and the like.

One of the principal objects of the invention is to simplify theoperating mechanism and eliminate the leve yoke and stationary housingof prior collet chucks.

Another object of the invention is to provide a lighter weight lesscostly chuck for a given work capacity.

- Another object is to provide a collet chuck in which the chuckingpressures ma be varied at will to enable the chucking of almost any typeof work under pressures close to the limit therefor without exceedingthe limit or distorting the workpiece. I

Another object is to more effectively shield the working parts of thechuck against infiltration of metal shavings and other injuriouselements.

Another object is to provide a simple means of connecting air pressureto the rotary chuck for operating the same.

An embodiment of the invention is illustrated in the accompanyingdrawings in which:

Figure 1 is a front elevation of the chuck with parts broken away andsectioned;

Fig. 2 is a vertical longitudinal section of the chuck takensubstantially axially thereof on line 2-2 of Fig. 1 and showing thechuck in retracted position;

Fig. 3 is a side elevation of the collet sleeve and pusher showing anoperating lever in section;

Fig. 4 is a sectional view similar to Fig. 2 showing the chuck inoperative gripping position upon a-workpiece;

' Fig. 5 is a fragmentary view corresponding to Fig. 3 showing theoperating lever in a position corresponding to the chuck position ofFig. 4, Fig. 6 is a detail view showing a cam slot with an operatinglever in a position corresponding to the chuck position of Fig. 4;

Fig. 7 is a detail section showing the passages and valve forapplication of air chuck;

Fig. 8 is a detail view similar to Fig. 6 with the lever in retractednon-chucking position; and I Fig. 9 is a detail section showing the construction taken on line 99 of Fig. 1.

The chuck has a cylindrical chuck body I with a flange 2 at its rear endfor bolting the same to a hollow rotary lathe spindle 3. bore of thebody I is of substantially greater diameter than the bore of the spindle3.

A collet 4 is disposed within body I and has itspressure to the Theinner outer end slit to provide radially movable collet fingers 5 withouter surfaces engaging a generally frusto-conical inner surface 6 ofthe bod I to efiect radial movement of the collet fingers in response tolongitudinal movement of collet 4 in body I.

Circumferential stress on the collet fingers 5 due to the transmissionof rotary forces thereby to the workpiece I is prevented by means ofkeys 8 secured to body I and disposed in the slots between the colletfingers.

A pusher sleeve 9 is adjustably threaded onto the rear end of collet 4and serves to operate the latter by moving the same in either directionlongitudinally in body I. For this purpose the sleeve 9 has a recess inits outer surface preferably in the form of a circumferential groove I0for receiving the inner projections II of operating levers I2.

There are preferably two operating levers I2 which are disposeddiametrically opposite each other in the chuck and extend generallylongitudinally of the body I in corresponding recesses I3 in its outersurface.

The inward projection II of the rear end of each lever I2 is journaledin a bushing in body I and extends therethrough into recess Ill ofpusher sleeve 9. The inner end of projection II has a flat side which isadapted to engage one wall of the groove I0 and to serve as a cam forpushing the sleeve 9 forwardl to effect operation of the collet fingers5 against surface 6.

Each lever I2 has an outward projection Id at its forward end carrying aroller I5 disposed in a recess It in a cylindrical slider I I encirclingbody I. One wall of each recess I6 which wall is a part of slider I'Iconstitutes a step cam I8 adapted to engage roller I5 and to move thelatter circumferentially of body I in response to longitudinal movementof slider [1, similar to the construction disclosed and claimed in thecopending application of the present inventor, Serial No. 717,212, filedDecember 19, 1946.

The slider I! is held against rotation relative to body I by means of astud I9 having a roller 20 riding in a groove 2| in the slider I'I.Roller 20 is disposed to engage a wall of groove 2| in opposition to theengagement of roller I5 and cam I8, to thereby hold slider I! againstturning under the action of the cam.

According to the present invention the slider I7 isoperated directly byair pressure without the intervention of lever mechanism. For thispurpose a power cylinder 22 encircles the slide and is formed by acircular cylinder head 23 bolted to flange 2, and a cylinder body andouter end 24 bolted to head 23.

The slider 11 bridges the gap of the cylinder on the inside and is theends to close the cylinder.

The slider 11 has a central circumferential flange 25 extending into thepower cylinder and sealed against the outer wall thereof to constitute apiston movable longitudinally in the cylinder in response to airpressure therein.

Air is admitted to and discharged from either end of the cylinder 22 bymeans of the valve spool 26 operable in a bore 21 in the wall 24 of thecylinder.

Valve bore 21 extends longitudinally of cylinder 22 in the outer wallthereof at the top of the chuck and has a port 28 connecting the same tothe rear end of the cylinder and a similar port 29 connecting the sameto the front end of the cylinder. A central exhaust port 3|] connectsbore 21 to the outside atmosphere through the wall 24.

The bore 21 is selectively supplied with compressed air at its oppositeends through nipples 3| and 32, respectively.

When the operator applies the end of a compressed air supply hose 33 tonipple 3|, air is admitted to the rear end of bore 21, as shown in Fig.2, pushing spool 26 to the right and admitting air to the rear end ofthe cylinder 22 through port 28. At the same time air is exhausted fromthe front end of cylinder 22 through port 29, bore 21 and exhaust port38. The piston 25 and its slide 11 are moved forwardly to release levers12 from the cams I8 and thereby release the workpiece 1.

When a new workpiece 1 is inserted, the operator connects supply hose 33to nipple 32 which supplies compressed air to the front end of bore 21moving spool 26 to the left and admitting air to the front end ofcylinder 22 through port 29. At the same time air is exhausted from therear end of cylinder 22 through port 28, bore 21 and exhaust port 30.The piston 25 and its slider [1 are moved rearwardly to apply cams [8 tothe corresponding levers l2 and effect gripping of workpiece 1 by colletfingers 5, as shown in Fig. 4.

After chucking the workpiece the air line 33 is disconnected and thechuck is free to turn with the spindle without drag. The steps in cam l8efiectively hold levers 12 to retain the chucking pressure on theworkpiece, and there is no danger of possible loss of chucking duringrotation of the workpiece. The operator cannot release the chuck untilit stops rotating and there is no danger of injury to the work by reasonof an accidental or negligent release of the chuck during its rotation.

The seals 34 between slider 11 and the cylinder heads 23 and 24, and theseal 35 between the piston flange 25 and the outer wall of the cylinder22 effectively prevent escape of air from the power end of the cylinder.

Seals 36 between the opposite ends of pusher sleeve 9 and body Ieffectively seals the same against chips and shavings tending to enterthe lever recesses.

A pin 31 looks each lever 12 in place in body I. For the purpose ofmachining and assembly, the slider I1 is made with a cylindrical insert38 in which recesses l6 and 2| are located. A screw 39 secures theslider 11 and insert 38 together. Recesses 16 open radially throughmember 38, and after the outer part of slider 11 is removed, and pins 31are removed, the levers 12 may be rebetween the ends sealed againstmoved outwardly through the recesses 16. Thereafter member 38 can beremoved longitudinally of body 1. Assembly of the parts is in thereverse order from that above referred to.

The invention provides a high power rotary collet chuck in which theslider is driven directly by a piston fixed thereto and operating in acylinder encircling the chuck.

Various embodiments of the invention may be employed Within the scope ofthe accompanying claims.

I claim:

1. In a collet chuck, a cylindrical rotatably mounted chuck body, aseries of collet fingers disposed inside said body and in engagementwith a frusto-conical cam surface thereof to operate in unison radiallyto grip and release a workpiece centrally thereof in response toopposite longitudinal movements of the collet fingers relative to thechuck body, a slider disposed outside the chuck body and encircling thesame to rotate therewith, a piston on said slider, a lever journaled insaid body and disposed to transmit motion from said slider to saidcollet fingers to operate the latter, a fluid pressure cylinder carriedby the chuck body and encircling said slider and disposed to providedirect fluid pressure against the piston of the slider for operation ofthe slider in opposite directions, and a valve spool in the wall of saidcylinder with a port leading therefrom to admit and discharge air fromsaid cylinder for actuation of the slider piston.

2. In a collet chuck, a cylindrical rotatably mounted chuck body, aseries of collet fingers disposed inside said body and in engagementwith a frusto-conical cam surface thereof to operate in unison radiallyto grip and release a workpiece centrally thereof in response toopposite longitudinal movements of the collet fingers relative to thechuck body, a slider disposed outside the chuck body and encircling thesame to rotate therewith, a lever journaled in said body and having aroller disposed in a recess in said slider to transmit motion from saidslider to said collet fingers to operate the latter, a fluid pressurecylinder carried by the chuck body and encircling said slider anddisposed to provide direct fluid pressure operation of the slider,coupling means in the Wall of said cylinder disposed to connect a powerfluid supply conduit thereto when the chuck is non-rotary to actuate thesame and to disconnect the conduit therefrom when the chuck is rotary,and step cam means in said slider to hold the roller of said lever atpredetermined collet operating positions to provide gripping of aworkpiece by said collet fingers after release of the fluid pressure insaid cylinder.

3. In a collet chuck, a cylindrical rotatably mounted chuck body, aseries of collet fingers extending from a collet and disposed insidesaid body and in engagement with a frusto-conical cam surface thereof tooperate in unison radially to grip and release a workpiece centrallythereof in response to opposite longitudinal movements of the colletfingers relative to the chuck body, a slider disposed outside the chuckbody and encircling the same to rotate therewith, a lever journaled insaid body and having a roller at the outer end disposed in a recess insaid slider to transmit motion from said slider to said collet fingersto operate the latter, a cam on the inner end of said lever, a sleevesecured to said collet and having a recess therein to receive said cam afluid pressure cylinder carried by the chuck said lever at predeterminedcollet operating positions to provide gripping of a workpiece by saidcollet fingers after release of the fluid pressure in said cylinder.

4. In a collet chuck, a cylindrical rotatably mounted chuck body, aseries of collet fingers disposed inside said body and in engagementwith a frusto-conical cam surface thereof to operate in unison radiallyto grip and release a workpiece centrally thereof in response toopposite longitudinal movements of the collet fingers relative to thechuck body, a slider disposed outside the chuck body and encircling thesame to rotate therewith, a lever journaled in said body and disposed totransmit motion from said slider to said collet fingers to operate thelatter, a fluid pressure cylinder carried by the chuck body andencircling said slider and disposed to provide direct fiuid pressureoperation of the slider, port connections through the Wall ofsaidcylinder for selectively admitting compressed air to either end ofsaid cylinder to effect movement of said slider in a correspondingdirection, means to hold said lever at predetermined collet operatinpositions to provide gripping of a workpiece by said collet fingersafter release of the fluid pressure in said cylinder, and said portconnections being adapted to receive selected connections with a sourceof air pressure for operating the chuck and which are disconnectedtherefrom during rotation of the chuck.

VIGO V. KROGH SUNDI.

REFERENCES CITED The following references are of record in the

